Hi all
I've read in several places that pure (green) tungsten is not suitable for use on inverter machines. Could someone please explain this to me? Does the tungsten suffer, or the inverter?
Also, has anyone used zirconiated tungsten much? I'd be interested to know if the arc start and heat tolerance is in fact significantly better than pure, or if it's just something the manufacturers like to say.
Cheers
The tungsten and weld quality suffer when using pure tungsten with inverters. I like the fancy tungsten like Layzer, trimix for the small inverter machines.
zirconiated works better than pure in my opinion but still does not have the current carrying capacity of others like 2% lanthanated.
zirconiated rounds nicely ...pretty much like pure on AC but holds up a bit better and can handle somewhat higher amperage than pure.
sometimes a balled electrode is fine but other times, its nice to use a tapered point ,,..or be able to weld at 200 amps with a 3/32" instead of needing to jump up to 1/8" or larger.
hope this helps
jody
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Thanks JD. Do you know what the physical reason behind it is that the tungsten suffers? I've read elsewhere that pure tungsten likes a classic sine wave instead of square. Makes me wonder if it would do fine on an inverter machine as long as it's set to sine wave form.
By the way I'm convinced that E3 and Layzr are the same blend. We got some E3 recently at work and the composition is written on the pack: lanthanum, yttrium and zirconium = layzr. It also contains 20% lanthanum which sounds insane. Had to read it twice. I like it too for the pointed tip as Jody says (thanks Jody for replying), but I get annoyed when the tip invariably splits into nodes over time. Same with 2% lanth and rare earth mix. The fact that the balled electrode stays the same shape consistently is really helpful to me on some parts where I have say 200 small pieces to weld and I've got my settings just right. Once the electrode tip starts to fray out too much, the welds come out different with the settings the same and I have to regrind the tip. With a single balled tip I can do all the parts the same and not think about it too much. Just the arc starts are so rough with pure tungsten, that's why I'm wondering if I can get an improvement by changing to zirconiated for these applications.
Something else I really like about E3 is its arc stability at low amperage. I do a lot of pulsed autogenous welds on 1 mm (40 thou for you guys) stainless with a background current of 3-5 amps. With a 1/16" 2% lanth tungsten I can get arc wander when the current drops down low. On E3 3/32" the arc stays completely crisp and stable. Pretty cool
From what you described, my opinion is that you would find .8% Zirconiated (White Band) ideal for what you described. It has just a slightly lower current carrying capacity vs EWLa-2. Additionally, it is said (in textbooks and elsewhere) that it resists contamination and also spitting on AC to a greater extent than any other electrode, which has been consistent with my own experience. In fact, a test question in school was based on this. It asked which electrode was used for X-Ray quality welds on AC due to contamination & spitting resistance. The answer was Zirconiated, which seemed strange at the time. I recommend .8% over .3% (brown band) since it should have exaggerated benefits over the .3% (however, I haven't used .3% before). I like having .8% Zr for Aluminum (AC) and 2% La for DC. It's convenient for me lol. Note that the differences between any decent electrodes are relatively subtle, but .8% Zr maintains a rounded tip geometry exceptionally well without forming nodules. It seems to get contaminated less frequently. Otherwise, there is little difference between it and 2% La (on AC). I'm not saying that this or any electrode will be any kind of silver bullet. It's more of a "nice to have" thing and mostly appeals to me for the sake of spending less time grinding tungsten, which of course is no one's favorite part of welding.
Thanks Alex, I'm convinced I need to give zirc a try... just have to convince my boss to buy some now
I don't know for certain what it is but I feel it has something to do with how inverters "make" their electricity. With inverters using relatively small input power but being able to put out much larger welding power has to do something wierd with the electricity. I bet it's different between each machine and the way the current runs thru the tungsten... I bet just trying to find the right tungsten that pairs well with your exact machine is probably the answer. I think you are on to something with wanting to try the zirc tungsten.
Its all about "how" you get the "pixies" angry before they come out the torch. Inverters use a rectifier, then invert the signal to a high frequency(like in the kilohertz), step the voltage down from that to achieve the high current, then I believe its just routed to + and - with a pulse width modulation to control the voltage. Something about the high frequency background signal in the output must be affecting the electrode. But man, they sure are easy to carry around!
Well said, Brian! I didn't even think of the high frequency adding another variable. So much going on in those little boxes... I do still love inverters
Here's a link to Diamond Ground Products' (DGP) Tungsten Electrode Guidebook. It's been my go-to reference for this topic.
It’s all fun and games until your tungsten explodes.